Q31.cpp

/*
Aledutron
SPPU 2019 SE DSL Lab
SPPU Computer Engineering Second Year (SE) Data Structure Lab (DSL) / Fundamentals of Data Structures (FDS) Assignments (2019 Pattern)
Youtube DSL / FDS Playlist Link: https://youtube.com/playlist?list=PLlShVH4JA0osUGQB95eJ8h5bTTzJO89vz&si=u12IYwo93Z7RU4e8

Problem Statement:
Group-E\Q31.cpp
A double-ended queue (deque) is a linear list in which additions and deletions may be made at either end. Obtain a data representation mapping a deque into a one☻dimensional array. Write C++ program to simulate deque with functions to add and delete elements from either end of the deque.

Explaination Video Link: https://www.youtube.com/watch?v=XD20iZgUfcA&list=PLlShVH4JA0osUGQB95eJ8h5bTTzJO89vz&index=15&pp=iAQB
*/

#include <iostream>
using namespace std;

class Deque
{
public:
	const static int size = 10;
	int array[size];
	int front = -1, rear = -1;

	bool isFull()
	{
		if ((front == 0 && rear == size - 1) || (rear == front - 1))
		{
			return 1;
		}
		return 0;
	}

	bool isEmpty()
	{
		if (front == -1 && rear == -1)
		{
			return 1;
		}
		return 0;
	}

	void insertFront(int x)
	{
		if (isFull())
		{
			cout << "Deque Overflow" << endl;
			return;
		}
		if (front == -1)
		{
			front = 0;
			rear = 0;
		}
		else if (front == 0)
		{
			front = size - 1;
		}
		else
		{
			front = front - 1; // front--;
		}

		array[front] = x;
		// cout << "Front is: " << front << endl;
	}

	void insertRear(int x)
	{
		if (isFull())
		{
			cout << "Deque Overflow" << endl;
			return;
		}

		if (rear == -1)
		{
			front = 0;
			rear = 0;
		}
		else if (rear == size - 1)
		{
			rear = 0;
		}
		else
		{
			rear = rear + 1; // rear++; rear += 1;
		}

		array[rear] = x;
		// cout << "Rear is: " << rear << endl;
	}

	void deleteFront()
	{
		if (isEmpty())
		{
			cout << "Deque Underflow" << endl;
			return;
		}

		if (front == rear)
		{
			front = -1;
			rear = -1;
		}
		else if (front == size - 1)
		{
			front = 0;
		}
		else
		{
			front++;
		}
	}

	void deleteRear()
	{
		if (isEmpty())
		{
			cout << "Deque Underflow" << endl;
			return;
		}

		if (front == rear)
		{
			front = -1;
			rear = -1;
		}
		else if (rear == 0)
		{
			rear = size - 1;
		}
		else
		{
			rear--;
		}
	}

	void display()
	{
		if (isEmpty())
		{
			cout << "Deque Underflow" << endl;
			return;
		}

		cout << "\nDeque contains: ";

		if (front < rear)
		{
			for (int i = front; i <= rear; i++)
			{
				cout << array[i] << " ";
			}
		}
		else if (front == rear)
		{
			cout << array[front];
		}
		else
		{
			for (int i = front; i < size; i++)
			{
				cout << array[i] << " ";
			}
			for (int i = 0; i <= rear; i++)
			{
				cout << array[i] << " ";
			}
		}
	}
};

int main()
{
	Deque q;
	q.insertFront(10);
	q.insertFront(16);
	q.insertFront(20);
	q.insertFront(13);
	q.insertRear(30);
	q.insertRear(37);
	q.display();
	q.deleteFront();
	q.deleteFront();
	q.deleteRear();
	q.deleteRear();
	q.deleteRear();
	q.deleteRear();
	q.display();
}